vt/console: try harder to print output when panicing

Jesse's initial patch commit said:

"At panic time (i.e.  when oops_in_progress is set) we should try a bit
harder to update the screen and make sure output gets to the VT, since
some drivers are capable of flipping back to it.

So make sure we try to unblank and update the display if called from a
panic context."

I've enhanced this to add a flag to the vc that console layer can set to
indicate they want this behaviour to occur.  This also adds support to
fbcon for that flag and adds an fb flag for drivers to indicate they want
to use the support.  It enables this for KMS drivers.

Signed-off-by: Dave Airlie <airlied@redhat.com>
Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>
Acked-by: James Simmons <jsimmons@infradead.org>
Cc: Alan Cox <alan@lxorguk.ukuu.org.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

diff --git a/drivers/char/vt.c b/drivers/char/vt.c
index 34bfb056d7a6c86a6cef686e194dbbb58a3b4cb0..82f64ac211911624df4cba181535d216b9529738 100644 (file)
--- a/drivers/char/vt.c
+++ b/drivers/char/vt.c
@@ -705,7 +705,10 @@ void redraw_screen(struct vc_data *vc, int is_switch)
                        update_attr(vc);
                        clear_buffer_attributes(vc);
                }
-               if (update && vc->vc_mode != KD_GRAPHICS)
+
+               /* Forcibly update if we're panicing */
+               if ((update && vc->vc_mode != KD_GRAPHICS) ||
+                   vt_force_oops_output(vc))
                        do_update_region(vc, vc->vc_origin, vc->vc_screenbuf_size / 2);
        }
        set_cursor(vc);
@@ -743,6 +746,7 @@ static void visual_init(struct vc_data *vc, int num, int init)
        vc->vc_hi_font_mask = 0;
        vc->vc_complement_mask = 0;
        vc->vc_can_do_color = 0;
+       vc->vc_panic_force_write = false;
        vc->vc_sw->con_init(vc, init);
        if (!vc->vc_complement_mask)
                vc->vc_complement_mask = vc->vc_can_do_color ? 0x7700 : 0x0800;
@@ -2506,7 +2510,7 @@ static void vt_console_print(struct console *co, const char *b, unsigned count)
                goto quit;
        }
 
-       if (vc->vc_mode != KD_TEXT)
+       if (vc->vc_mode != KD_TEXT && !vt_force_oops_output(vc))
                goto quit;
 
        /* undraw cursor first */
@@ -3784,7 +3788,8 @@ void do_unblank_screen(int leaving_gfx)
                return;
        }
        vc = vc_cons[fg_console].d;
-       if (vc->vc_mode != KD_TEXT)
+       /* Try to unblank in oops case too */
+       if (vc->vc_mode != KD_TEXT && !vt_force_oops_output(vc))
                return; /* but leave console_blanked != 0 */
 
        if (blankinterval) {
@@ -3793,7 +3798,7 @@ void do_unblank_screen(int leaving_gfx)
        }
 
        console_blanked = 0;
-       if (vc->vc_sw->con_blank(vc, 0, leaving_gfx))
+       if (vc->vc_sw->con_blank(vc, 0, leaving_gfx) || vt_force_oops_output(vc))
                /* Low-level driver cannot restore -> do it ourselves */
                update_screen(vc);
        if (console_blank_hook)

diff --git a/drivers/gpu/drm/i915/intel_fb.c b/drivers/gpu/drm/i915/intel_fb.c
index 54acd8b534df4bd092c71f4e8ce0998b7cd9dc09..a79525f434a8fae8a4654927050f285ff49f20e0 100644 (file)
--- a/drivers/gpu/drm/i915/intel_fb.c
+++ b/drivers/gpu/drm/i915/intel_fb.c
@@ -130,7 +130,7 @@ static int intelfb_create(struct intel_fbdev *ifbdev,
 
        strcpy(info->fix.id, "inteldrmfb");
 
-       info->flags = FBINFO_DEFAULT;
+       info->flags = FBINFO_DEFAULT | FBINFO_CAN_FORCE_OUTPUT;
        info->fbops = &intelfb_ops;
 
        /* setup aperture base/size for vesafb takeover */
@@ -148,8 +148,6 @@ static int intelfb_create(struct intel_fbdev *ifbdev,
        info->fix.smem_start = dev->mode_config.fb_base + obj_priv->gtt_offset;
        info->fix.smem_len = size;
 
-       info->flags = FBINFO_DEFAULT;
-
        info->screen_base = ioremap_wc(dev->agp->base + obj_priv->gtt_offset,
                                       size);
        if (!info->screen_base) {

diff --git a/drivers/gpu/drm/nouveau/nouveau_fbcon.c b/drivers/gpu/drm/nouveau/nouveau_fbcon.c
index 2fb2444d23221d8684683dedb036b14f3034220d..099f637264aa7ba8b39e6a22977c570a6b213a20 100644 (file)
--- a/drivers/gpu/drm/nouveau/nouveau_fbcon.c
+++ b/drivers/gpu/drm/nouveau/nouveau_fbcon.c
@@ -250,6 +250,7 @@ nouveau_fbcon_create(struct nouveau_fbdev *nfbdev,
                info->flags = FBINFO_DEFAULT | FBINFO_HWACCEL_COPYAREA |
                              FBINFO_HWACCEL_FILLRECT |
                              FBINFO_HWACCEL_IMAGEBLIT;
+       info->flags |= FBINFO_CAN_FORCE_OUTPUT;
        info->fbops = &nouveau_fbcon_ops;
        info->fix.smem_start = dev->mode_config.fb_base + nvbo->bo.offset -
                               dev_priv->vm_vram_base;

diff --git a/drivers/gpu/drm/radeon/radeon_fb.c b/drivers/gpu/drm/radeon/radeon_fb.c
index dc1634bb0c11e7f0bdcda150e330fa5fa1523c2c..dbf86962bdd16a5741c3de1369c4ebe7d6c36d29 100644 (file)
--- a/drivers/gpu/drm/radeon/radeon_fb.c
+++ b/drivers/gpu/drm/radeon/radeon_fb.c
@@ -224,7 +224,7 @@ static int radeonfb_create(struct radeon_fbdev *rfbdev,
 
        drm_fb_helper_fill_fix(info, fb->pitch, fb->depth);
 
-       info->flags = FBINFO_DEFAULT;
+       info->flags = FBINFO_DEFAULT | FBINFO_CAN_FORCE_OUTPUT;
        info->fbops = &radeonfb_ops;
 
        tmp = radeon_bo_gpu_offset(rbo) - rdev->mc.vram_start;

diff --git a/drivers/video/console/fbcon.c b/drivers/video/console/fbcon.c
index 3b3f5749af925c83d055fa41df0a1c6baed92e5a..26bf7cbfecc2748401181c1a13354cd817dbd2df 100644 (file)
--- a/drivers/video/console/fbcon.c
+++ b/drivers/video/console/fbcon.c
@@ -283,7 +283,8 @@ static inline int fbcon_is_inactive(struct vc_data *vc, struct fb_info *info)
        struct fbcon_ops *ops = info->fbcon_par;
 
        return (info->state != FBINFO_STATE_RUNNING ||
-               vc->vc_mode != KD_TEXT || ops->graphics);
+               vc->vc_mode != KD_TEXT || ops->graphics) &&
+               !vt_force_oops_output(vc);
 }
 
 static inline int get_color(struct vc_data *vc, struct fb_info *info,
@@ -1073,6 +1074,7 @@ static void fbcon_init(struct vc_data *vc, int init)
        if (p->userfont)
                charcnt = FNTCHARCNT(p->fontdata);
 
+       vc->vc_panic_force_write = !!(info->flags & FBINFO_CAN_FORCE_OUTPUT);
        vc->vc_can_do_color = (fb_get_color_depth(&info->var, &info->fix)!=1);
        vc->vc_complement_mask = vc->vc_can_do_color ? 0x7700 : 0x0800;
        if (charcnt == 256) {

diff --git a/include/linux/console_struct.h b/include/linux/console_struct.h
index 38fe59dc89aefaa97871270371f28ff74bf8ca3f..d7d9acdccffb21e16367b1f69980cae0b409a744 100644 (file)
--- a/include/linux/console_struct.h
+++ b/include/linux/console_struct.h
@@ -105,6 +105,7 @@ struct vc_data {
        struct vc_data **vc_display_fg;         /* [!] Ptr to var holding fg console for this display */
        unsigned long   vc_uni_pagedir;
        unsigned long   *vc_uni_pagedir_loc;  /* [!] Location of uni_pagedir variable for this console */
+       bool vc_panic_force_write; /* when oops/panic this VC can accept forced output/blanking */
        /* additional information is in vt_kern.h */
 };
 

diff --git a/include/linux/fb.h b/include/linux/fb.h
index 0c5659c41b01c502160ca089bd758a36963f7918..f0268deca658be33a9d06d81469e45e3933ed0c3 100644 (file)
--- a/include/linux/fb.h
+++ b/include/linux/fb.h
@@ -825,6 +825,10 @@ struct fb_tile_ops {
  */
 #define FBINFO_BE_MATH  0x100000
 
+/* report to the VT layer that this fb driver can accept forced console
+   output like oopses */
+#define FBINFO_CAN_FORCE_OUTPUT     0x200000
+
 struct fb_info {
        int node;
        int flags;

diff --git a/include/linux/vt_kern.h b/include/linux/vt_kern.h
index 7f56db4a79f02e02810c3018b34b8a52af2c24a6..56cce345aa8d6e89ea9a5c81747256ffee326b22 100644 (file)
--- a/include/linux/vt_kern.h
+++ b/include/linux/vt_kern.h
@@ -100,6 +100,13 @@ extern int unbind_con_driver(const struct consw *csw, int first, int last,
                             int deflt);
 int vty_init(const struct file_operations *console_fops);
 
+static inline bool vt_force_oops_output(struct vc_data *vc)
+{
+       if (oops_in_progress && vc->vc_panic_force_write)
+               return true;
+       return false;
+}
+
 /*
  * vc_screen.c shares this temporary buffer with the console write code so that
  * we can easily avoid touching user space while holding the console spinlock.